On Thu, Jul 4, 2013 at 6:57 PM, Iulian Stana <julian.stana at gmail.com> wrote:
> After some of Matt's remarks I write a new API proposal for c-hglib.
> I come with some answers for Matt's questions and a header file for
> the level 0 ( here are some of the basic functions that will help me
> to achieve the API purpose)
> I would like to get feedback to know if I am on the good path.
>
>
> What does this return?
> - int hg_rawread(hg_handle *handle, char *buffer, size_t sizebuff);
> - int hg_rawcommand(hg_handle *handle, const char *command);
> - int hg_close(hg_handle *handle);
>
> .h file:
>
> typedef struct hg_handle hg_handle;
> typedef struct hg_header{
> char channel;
> uint32_t length;
> } hg_header;
>
> /* return the handle for a connection */
> hg_handle* hg_open(const char *path);
>
> /* The function returns 0 if successful, -1 to indicate an error, with
> errno set appropriately. */
> int hg_close(hg_handle *handle);
>
> /* The function returns 0 if successful, -1 to indicate an error, with
> errno set appropriately. */
> /* It's just sending the command to the cmdsrv.*/
> int hg_rawcommand(hg_handle *handle, const char *command);
>
> /* The function returns the number of bytes read. On end-of-file, 0 is
> returned, on error it returns -1, setting errno to indicate the type of
> error that occurred. */
> int hg_rawread(hg_handle *handle, char *buffer, size_t sizebuff);
>
> /* The function returns the number of bytes written to the file. A return
> value of -1 indicates an error, with errno set appropriately. */
> int hg_rawsend( hg_handle *handle, char *buffer);
>
> /* The function returns the channel for the next chunk*/
> char hg_channel(hg_handle *handle);
>
> /* The function returns the header in advance. */
> hg_header hg_ rawchunk(hg_handle *handle);
>
> /* The function returns the exitcode received from cmdserver.*/
> int hg_exitcode(hg_handle * handle);
>
> /* It's just a proposal for how to send/receive data through connection
> while 1:
> switch(hg_channel(handle)):
> case 'r':
> hg_exitcode(handle);
> break;
> case 'o':
> /* Make something with data save it into a data structure*/
> hg_rawread(handle, buffer , size);
> save_into_out_channel(buffer);
> case 'e':
> hg_rawread(handle, buffer , size);
> save_into_err_channel(buffer);
> case 'I':
> case 'L':
> hg_rawsend(handle, buffer);
> */
>
> This doesn't mean "figure out how to wrap these commands" in C code,
> instead it means "figure out how to expose enough of the protocol to the
> user so that they can run these sorts commands"
> In figuring out what needs to be in the level 0 API, here are the commands
> you should probably figure out a story for:
>
> a) hg init <- doesn't start with a repo
> In this case, I will create a new process were I will execute the init
> command, to create the new repo. After this, I will establish the
> connection through pipes, with the cmdserver.
> For the clone command, there I will execute the same steps.
> The return in those cases will be the handle for the connection.
>
> b) hg log <- can produce huge output
> I know that some repo could have a huge log, but I don't know if the user
> will use that huge output. My single thought right now is to set a limit
> for the huge mass of data.
> “The memory is full, the log data for this repo it's bigger than MAX_SIZE,
> you can specify a file were the data to be store.”
> I don't know if this is the best solution... Other ideas are welcome.
>
Limiting the amount of data sounds sensible, but why write it to a file?
What about a cursor-like interface, similar to those returned by SQL
queries?
>
> c) hg import - <- wants a patch fed to it from client
> If patch is a list of files or a file-like, then the input for the command
> server will be from those files. In this case the data will be send line by
> line to the server.
>
Note that the command server may ask for line-input or input in bulks with
a size hint: http://mercurial.selenic.com/wiki/CommandServer#Channels
I don't remember what happens in import, but you shouldn't assume one or
the other.
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